First iteration on introducing a NLM converter.

Not working yet.
Zwischenpush.
Hack no longer needed.
Remove obsolete index specifications.

Indexes shall be created dynamically.
Add a 'year' to 'article_citation'.
Add annotation type 'formula_reference'.
Style tweakz.
File view.
modifying supplemental file view
Composite business.
Tweaks.
Added whoami for debugging.
Let Lens.Article support nested nodes.
Clean up.
Refactored nodeTypes to provide Model and View separated.
Simplify figure node type.
Caption rendering.
Updated copy of substance-article's TextView.
Merge branch 'nlm_converter_m' of https://github.com/elifesciences/lens-article into nlm_converter_m
Simplify.